1. Field of the Invention
The present invention relates to a peer-to-peer (P2P) type information communication system including a plurality of node devices mutually connected through a network, a method thereof, and the like.
2. Discussion of Related Art
A technology of peer-to-peer has been paid attention recently. With respect to a peer-to-peer type information communication system, in an overlay network logically built using a distributed hash table (hereinafter referred to as DHT), each node device does not necessarily recognize link information (e.g. IP address) to all the node devices participating in the overlay network but retains (memorizes) only link information to a portion of node devices obtained at the time of participation, and data inquiry or the like is made based on such the link information.
In such the overlay network, even in a case where participation and withdrawal (separation) of node devices are often repeated, a load thereto should be appropriately distributed. There is disclosed in “Lightweight Load Balancing for Distributed Hash Table” by Toshio Oka, Hiroyuki Morikawa, Tomonori Aoyama; Technical report of the Institute of Electronics, Information and Communication Engineers Feb. 5, 2004, Vol. 103, No. 650, p. 7-12, that an art of an overlay network wherein load is appropriately distributed even in a case where participation and withdrawal (separation) are often repeated.